Choi H, Thacker EL, Longstreth WT, et al. - In older adults with and without epilepsy, this study calculated and compared rates of cognitive decline. Researchers designed the Cardiovascular Health Study (a population‐based longitudinal cohort study) including a total of 5,888 US adults aged 65+. They evaluated the cognitive function annually with the Modified Mini‐Mental State Exam (3MS) and Digit Symbol Substitution Test (DSST). Linear mixed models were applied to calculate average rates of decline in 3MS and DSST scores by epilepsy status (prevalent, incident, or no epilepsy), adjusted for risk factors linked with cognitive decline. Compared with no epilepsy, the rate of decline in 3MS was significantly faster in prevalent epilepsy and after incident epilepsy. Compared to those with no epilepsy, older adults with prevalent epilepsy had a significantly lower initial DSST score and faster rate of decline. There was a synergistic interaction between prevalent epilepsy and apolipoprotein E gene (APOE) ε4 (ApoE4), whereby prevalent epilepsy and ApoE4 together correlated with a 1.51 points faster annual decline in 3MS than was expected if prevalent epilepsy and ApoE4 did not interact. Futures study is needed to evaluate biological mechanisms and possible interventions to mitigate cognitive decline.